Step 12: Hooking it up!

Step 13: Closing Thoughts

I hope you guys enjoyed my instructable, as this is my very first step by step instructable. I tried to complete, giving as many details I could think...

I'm going to show you how to make a 7 segment display with LEDS. Combine with Arduino to create countdown timers, simple text, and more. I like to make original projects. I searched the whole of instructables and didn't find one like this. In fact, I searched google, and did not find any results. I thought of this when I couldn't get my real 7-segment display to work! Enjoy! It's amazing what you can accomplish with LEDs!

How the project works: All the anodes of one row are connected together. There are 3 LEDs in one row. See picture. When you supply voltage to the row, the whole row lights up. So, connecting all the cathodes together, I used Arduino to program each row to turn on and off. In the picture above, here are the rows that Arduino is turning on: Row 1, 2, 4, 5, 6, 7,

Remember, the way instrucables is set up, the pictures come first, then the explanation.

If you are interested in making this project, please read over this whole instrucable BEFORE you start and get confused! And, please, don't forget too look at ALL the pictures and the boxes for them.

Here is a video of my the display using numbers. The next is it displaying the word, ALPHA.

1. What did you make? The idea started when I was getting frustrated because I couldn't get my 7 segment display to work with one of my ICs, so I decided upon making my own, so that I'd could control it in basically any way I wanted, including simple text.2. How did you make it? The very first thing I did was get out my sketchbook and draw down my ideas, and how I would connect them together. I started working on this project at 11:30 pm, and kept on going until about 4:30 A.M.. I kept on running into obstacles, such accidentally soldering the negative and positive leads of 3 LEDs together! I made it with 27 LEDs, a small piece of perf board, some basic tools, wires, and most importantly my newly-bought Arduino. I did this project by myself.3. Where did you make it? Well. . . I made this project all in my room, on my makeshift desk,and downstairs in our office (for programming Arduino). The more I programmed, the more problems arose, so I had to keep on running back and forth between my soldering un upstairs and the computer down stairs! I wore a path through my carpet, down the creaking wooden stairs, across the tile, over the wooden floor in my office to the computer. How did the project connect to other activities in my life? I was able to count this for my schoolwork! I aslo used this project as a show-off to Bravo, (another group in my activities, I'm ALPHA)4. What did you learn?

Where do I start? I learned that I should have used a resistor for each LED, instead of one resistor

The BIGGEST thing I learned was how to program my Arduino!

I learned some more techniques about soldering

I also learned a little bit more about LEDs themselves

If I could do anything differently i would have bought 27 resistors and soldered them to each LED!What am I proudest of? My success! I would have never thought it woudbe such an interest with my friends!

Wow, I just got finished reading about using Arduino's analog pins yesterday! Ok, here's what I found. 7 segment display = 7 pins. 16 segment display = 16 pins. The Arduino Uno only has 13 digital pins. But, you can set up Arduino's analog pins to work as digital pins. Arduino Uno has 5 analog pins, and making those work as digital, thats 13 + 5 = 18. Yes, you could make a 16 segment display. Interesting thought. I might have to try that!

Here's a link for more reading. http://arduino.cc/en/Tutorial/AnalogInputPins

I love it!! I am going to make a clock using this I have all of the LEDs soldered already I am just trying to decide how I want to control it. I don't know if I want to use an Arduino or a PIC or 74XX logic gates.

this is the picture of my LED 7-segment display, not so good as yours. and it still on my protoboard, I will change it to PCB printed soon :)

but, If I want to add a push button for the input and used for changing the characters, can you help me what the code should be add as an interrupt? I'm sorry if I'm so greedy with the question, I'm just curious :|

Sorry if I ask too much. But is it okay for not using resistor for each led? and just solder a 100-300 ohm resistor in series with the potentiometer? Because my friends told me that the LED gonna be frying all at once if I didn't put a resistor for each row/led. I'm so confused.

". . . LEDs have what is called a positive temperature coefficient. If they get hotter, they pass more current. In a parallel chain, one will get hotter and steal current from the others,which will get cooler, and give more current to the hotter LED which will get hotter- and so on. . . "

If one (or worse, several) LED(s) are getting an too much current, it will die, leaving you sorry you wasted 27 LEDs and a bunch of soldering. At the time I didn't know this, but I'm going to be adding the resistor step here shortly. (so I don't look like a dumbo) :D